Guangzhou Baiyun Airport, China’s second-busiest, has begun work on an expansion program that will more than double its designed capacity and strengthen its bid to be the leader among five airports in the Pearl River Delta.

Start of the work follows confirmation by the national government last month that Guangzhou will serve as one of China’s three main international aviation gateways, even though the great majority of southern China’s intercontinental passengers connect at Hong Kong International Airport.

Guangzhou’s Communist Party Committee also decided to press ahead with studies for a second airport for the city, although no details are given except that it will be in the southern districts. Baiyun, home of China Southern Airlines, is in the North.

Competition among airports in the well-developed Pearl River Delta is already fierce. Apart from Baiyun and Hong Kong International, the region has Shenzhen Bao’an, Macao International and, weakest of the five, Zhuhai Sanzao.

The expansion is intended to prepare Baiyun to handle 80 million passengers in 2020, compared with 45 million last year and more than 50 million expected this year. The current runways and terminal were designed for 25 million but can cope adequately with 35 million, say local media, so the facility is now grossly overloaded.

The main features of the upgrade are a 3,800 X 60 meter (12,500 X 200 ft.) runway able to handle any class of commercial aircraft and a 595,000 square meter Terminal 2, says the National Development and Reform Commission, the national authority that authorized the work. The runway is due to be completed in 2014 and the terminal in 2016.

The two runways cannot handle more than 1,000 movements a day and are nearing capacity.

According to many local media reports, the third runway will be only 400 meters (1,300 ft.) east of the current eastern runway. Under U.S. rules, parallel runways less than 2,500 ft. apart are treated as a single runway.

The airport’s landing guidance system will be upgraded to Category 2, and the airport will get a new air traffic control operations building, new radars, more car parks, a metro station, and four 10,000-cubic-meter fuel tanks that will be supplied from outside the facility by a 100 km (60 mi.) pipeline.

The budget for the expansion is 18.9 billion yuan ($3 billion), of which 800 million yuan will come from the aviation development fund.

This is likely to be the last major expansion of Baiyun. Zhang Kejian, the chairman of the facility’s listed operating company, said last year that international experience suggests airports tend to become more efficient as they grow, but not past a capacity of 80 million passengers a year, or at most 100 million. Beyond that, it is better to build another airport, he said. Similarly, Beijing has decided to build another airport, rather than further expand Capital Airport, whose designed capacity is 85 million passengers a year.

Beijing and Shanghai are the other two cities designated as main gateways for China.